Determining the environmental burdens and resource use in the production
of agricultural and horticultural commodities

Executive SummaryThe research addresses key questions underpinning the
development of sustainable production and consumption systems that are
based on domestically produced agricultural and horticultural commodities.
It quantifies the resource use and environmental burdens arising from
the production of ten key commodities and delivers accessible models
that enable resource use and emissions arising from various production
options in England and Wales to be examined in detail. The commodities
examined are: bread wheat, potatoes, oilseed rape, tomatoes, beef, pig
meat, sheep meat, poultry meat, milk and eggs.

The overall research aim agreed with Defra was to model the environmental
burdens and resource use involved in producing ten agricultural and
horticultural commodities using the principles of Life Cycle Assessment
(LCA), and to deliver these models in a user-accessible form such as
Microsoft Excel. The specific project objectives were to identify and
define the major productions systems in England and Wales and the related
process flow charts, to establish the relevant mass and energy flows
and other necessary data and their uncertainties, to code the LCA models
in a package, such as Microsoft Excel, with all the main data readily
accessible and published, to use the LCA model to analyse these production
systems and demonstrate that the model can compare production systems
and can identify high risk parts the systems, and to publish and publicise
the research outputs.

All inputs into on-farm production for each commodity were traced back
to primary resources such as coal, crude oil and mined ore. All activities
supporting farm production, such as feed production and processing,
machinery and fertiliser manufacture, fertility building and cover crops,
were included. The system included soil to a nominal depth of 0.3 m.
Where appropriate (tomatoes, potatoes), commodities were defined as
national baskets of products, for example tomato types such as loose
and on-the-vine tomatoes, each included as their proportion of national
production. Abiotic resources used (ARU) were consolidated onto one
scale based on relative scarcity. Individual emissions, such as carbon
dioxide (CO2) and nitrous oxide (N2O), were quantified and aggregated
into impacts for global warming (GWP), eutrophication (EP) and acidification
(AP). Organic production systems were analysed for each commodity, as
well as variations on non-organic (or contemporary conventional) production.

Interactions between inputs, outputs and emissions were represented
by functional relationships derived from process models wherever possible,
so that as systems are modified they respond holistically to specific
changes. For example, crop yields and nitrogen supply, dairy cow diet
formulation and milk yield, and grass productivity, emissions, animal
grazing and fertiliser applications are functionally related. Process
simulation models were also used to derive the long term outcomes of
nitrate leaching, soil, crop type and nitrogen supply.